<template>
  <div class="pagination">
    <button @click="beforePage" :disabled='pageNo==1'>上一页</button>
    <button v-if="startNumAndendNum.start!==1" @click="$emit('getPageNo',1)" :class="{active:pageNo===1}">1</button>
    <button v-if="startNumAndendNum.start>2">···</button>

    <button v-for="page,index in continues" :key="index" :class="{active:pageNo===index+startNumAndendNum.start}"
    @click="$emit('getPageNo',index+startNumAndendNum.start)">{{index+startNumAndendNum.start}}</button>
    
    <button v-if="startNumAndendNum.end<=totalPage-2">···</button>
    <button v-if="startNumAndendNum.end!==totalPage" @click="$emit('getPageNo',totalPage)" :class="{active:pageNo===totalPage}">{{totalPage}}</button>
    <button @click="nextPage" :disabled='pageNo==totalPage'>下一页</button>
    <button style="margin-left: 30px">共 {{total}} 条</button>
  </div>
</template>

<script>
// 当前是第几个数据 pageNo
// 当前页展示多少条数据  pageSize
// 整个分页器总共多少条数据 total
// 连续页码的个数 contiunes
  export default {
    props:['pageNo','total','continues','pageSize'],
    name: "Pagination",
    computed:{
        totalPage(){
            // 向上取整
            return Math.ceil(this.total/this.pageSize);
        },
        startNumAndendNum(){
          const {continues,pageNo,totalPage,} = this
          let start = 0, end = 0;
          if(continues>=totalPage){
            start = 1
            end = totalPage
          }else{
            start = this.pageNo - parseInt(continues/2)
            end = this.pageNo + parseInt(continues/2)
            if(start<1){
              start = 1
              end = continues
            }
            if(end>totalPage){
              end = totalPage
              start = totalPage-continues+1
            }
          }
          return {start,end}
        }
    },
    methods:{
      beforePage(){
        this.pageNo--
        this.$emit('getPageNo',this.pageNo)
      },
      nextPage(){
        this.pageNo++
        this.$emit('getPageNo',this.pageNo)
      }
    }
  }
</script>

<style lang="less" scoped>
  .pagination {
    text-align: center;
    button {
      margin: 0 5px;
      background-color: #f4f4f5;
      color: #606266;
      outline: none;
      border-radius: 2px;
      padding: 0 4px;
      vertical-align: top;
      display: inline-block;
      font-size: 13px;
      min-width: 35.5px;
      height: 28px;
      line-height: 28px;
      cursor: pointer;
      box-sizing: border-box;
      text-align: center;
      border: 0;

      &[disabled] {
        color: #c0c4cc;
        cursor: not-allowed;
      }

      &.active {
        cursor: not-allowed;
        background-color: #409eff;
        color: #fff;
      }
    }
  }
</style>